For a decent starting point and primary resource to research yourselves:

HK has many milestones in its history, being 69 years old aside, for you fans of phallic humor such as myself on ERBoH.

The first and most prominent is that, despite popular belief, they pioneered the polymer handgun before Glock did with its G17 pistol. The HK VP70 (In German, roughly "Volkspistol 70" or "People's Handgun,